1. Field of the Invention
The present invention relates to methods for recovering polyvalent antimony catalyst(s) from a halohydrocarbon chlorination or cracking process for reuse as a catalyst in the chlorination of halohydrocarbons or cracking of halohydrocarbons.
2. Description of the Related Art
Chlorinated hydrocarbons are useful as feedstocks for the manufacture of fluorinated hydrocarbons, such as hydrofluoroolefins (HFOs). Hydrofluoroolefins can, for example, be used as, or as components of, refrigerants, polyurethane blowing agents, fire extinguishing agents, and foaming agents. For purposes of illustration, 1,1,1,2,3-pentachloropropane can be used as an intermediate in the manufacture of 1,1,2,3-tetrachloropropene, which is a feedstock for the preparation of HFOs, and in the preparation of the herbicide trichloroallyl diisopropyl thiocarbamate, which is commonly referred to as Triallate.
The preparation of chlorinated hydrocarbons typically involves reactions that can require a number of steps, extended periods of time to complete, and/or reduced reaction temperatures and related refrigeration equipment, which can have increased economic costs associated therewith. It would be desirable to develop new methods of forming chlorinated hydrocarbons that require less steps and/or reduced reaction times relative to existing methods.
Antimony trichloride and antimony pentachloride can be used as catalysts in the chlorination of hydrocarbons and the cracking of halohydrocarbons to prepare olefins or haloolefins. However, the removal of the antimony compounds from the desired products can be very complicated and costly due to their solubilities and volatilities. Antimony removal techniques, such as acidic or basic washes, carbon filtration, adsorption onto alumina and silica, etc., render the antimony catalysts unusable for process recycling. It is desirable to recover the antimony compounds for recycle or reuse in chlorination and cracking processes.